End-thrust counterbalance for centrifugal pumps and other machinery.



. YEATMAN. END THRUST COUNTERBALANCE FOR CENTRIFUGAL PUMPS AND OTHER MACHINERY.

APPLICATION FILED-081130, I914.

Patented Dec. 28, 1915.

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JOHN A. YEATMAN, 0F OAKLAND, CALIFORNIA, ASSIGNOR 130 UNITED IRON WORKS, A CORPORATION OF CALIFORNIA.

Specification of Letters Patent.

Patented Dec. 28, 1915.

I Application filed October 30, 1914. Serial No. 869,414.

State of California, have made a new and useful invention-to wit: An End-Thrust Counterbalance for Centrifugal Pumps and other Machinery; and I do hereby declare the following to be a full, clear, concise, and eXact description of the same.

Generically the object of my invention is to provide in one pump structure two counterbalancing devices for the runner, so arranged that one of them will operate under normal conditions to maintain equilibrium of the runner during quiescence of the other, and the latter will automatically be brought into operation to restore that equilibrium when it is disturbed by reason of the inefiiciency of the first counterbalance. And more specifically my object is to combine in one pump structure a counter-balancing device of the calculated type with one of the automatic type for attaining the object above referred to.

In this specification and the annexed drawings, I have shown the two counterbalancing devices as being ofthe calculated and automatic types respectively, that being considered the best form in which I have contemplated embodying my invention; but it is to be understood that I do not limit myself to such form, nor to the specific constructions shown or any one thereof, and that by the claims following the description I desire to cover the invention in whatever form it may be embodied.

It is well known that in the operation of centrifugal pumps the discharge pressure between the runner and its case is not equal at all times to the total discharge pressure in the involute of the case or discharge pipe of the pump, and that these variations will cause unequal pressures on the opposite sides of the runner, thereby producing a tendency in the runner to move out of central alinement, which result impairs the efliciency of operation. When the pump is of the vertical shaft type, this end thrust is augmented by the weight of the runner and shafting. In the present state of the art, there are two methods mostly in vogue for counter-balancing this end thrust, one known as thecalculated balance and the other. as the automatic requires no detailed description. Each has certain merits and at the same time certain defects, and itis one of the objects of my invention to provide a counter-balancing device which will retain and preserve the merits, and at the same time eliminate the defects, of the said two methods as nearly as possible. With that end in View, I have herein shown as combined in one pump structure the general features of the two said methods with such modifications, additions and interrelation of parts as are necessary to attain the end in view, and thereby I have provided a combined calculated and automatic counter-balancing device for the end thrust of centrifugal pumps and similar machinery which is of simple construction and great efficiency.

Referring to the drawings accompanying this specification and annexed thereto, Figure 1 is a vertical section of a vertical shaft centrifugal pump showing the counter-balance chamber of my invention. Fig. 2 is a fragmentary section of the lower part of the pump on a larger scale. Fig. 3 is a cross section taken on the line AA Fig. 2.

My invention is particularly adapted to be used in connection with vertical shaft centrifugal pumps, and I have illustrated such a pump in the drawings, but it may be applied also to horizontal shaft pumps. The pump consists of a case 2 having the usual involute chamber 3, suction inlets 4;,

and discharge outlet 5. Within the case 2 and attached to the vertical drive shaft 6, is the runner 7, which is arranged so that it lies substantially centrally of the case when the pump is in operation. A collar 8, secured to the shaft 6, supports the shaft and runner when the pump is not in operation, and is so placed that it is lifted out of contact with'the upper part of the pump framing 9, when the pump is in operation.

The runner 7 is provided on opposite sides with flanges 12-13, which form running joints to hold the runner alined. The flange 12 on the upper side of the runner forms a running joint with the case 2, and the flange 13 on the lower side forms a run ning joint with the ring 14 secured to the case. This ring 14 is preferably formed separable from the case so that it may readily be removed when worn and anew ring substituted; but it may be dispensed with balance, each of which .is wellknown: and, and the side of. the case beillsedif desiredl- Secured to the flange 13 is an annular plate 15 having a depending flange 16 formed at its inner periphery. This flange forms a running joint with the flange or vertically extending portion 17 of the plate 18, which is preferably formed integral with the bottom closing plate 19. The plate 18 is spaced from the plate 19 and is held in position with respect thereto by the ribs 21,

thereby forming a chamber 22 between the plates 18 and 19, the top of the chamber being closed by the plate 15 secured to the runner. The plate 19 is formed with an aperture therein leading away from the pump which serves as an outlet for the water in the chamber 22 as hereinafter described. This outlet is preferably formed of a hollow nipple 23, screw-threaded into the plate 19, so that its position may be adjusted vertically.

At the lower'end of the runner 7 is a piston 24, which may be a continuation of the shaft 6, and the piston extends through a packed bearing in the plate 18 and into the nipple 23. The piston moves vertically with the runner, and the movement of the piston opens and closes the nipple 23 and thereby controls the discharge of water from chamber 22 through the nipple 23.

Water under pressure is supplied to the chamber 22 through the running joint between the flange 13 and the ring 1 1, and

since this joint is larger than the joint between the flanges 16 and 17, water under pressure is accumulated in the chamber 22, which exerts an upward pressure on the runner thereby tending to counteract the down thrust of the runner. Under normal running conditions when the water pressure in the chamber 22 exceeds the pressure on the opposite side of the runner and thereby the runner tends to move upward out of alinement with the involute, said pressure is relieved by the escape of water from said chamber through the joint between the flanges 16 and 17 and back into the runner through ports 25, so that the runner will be maintained in alinement with the involute. When the pump runs under such conditions that the water cannot escape rapidly enough through the joint between the flanges 16 and 17 to maintain the runner and involute in alinement with each other, the water pressure will raise the runner and withdraw the piston 21 from the nipple 23 and allow the water in the chamber 22 to discharge through the nipple 23 until the water pressure in said chamber is reduced to such an extent that the runner moves back down into alinement with the involute and the piston 24 closes the nipple, thereby reestablishing the initial condition.

In constructing this device the pressure chamber 22 is calculated beforehand to be of such dimensions as will ordinarily afford pressure sufiicient to counter-balance the end thrust of the runner when nipple 23 is closed, and in making this calculation a portion of the normal pressure area at the bottom of the runner, as heretofore used, has been excluded by the interposition of the plate 18 having the upturned flange 17 contacting with the downturned flange 16 of plate 15. Consequently, this excluded area is relieved from the action of pressure, so that the remaining area liable to pressure is the bottom of plate 15, Up to this point the balance is a calculated one, but one having a portion of the ordinary pressure area excluded, which construction is a great advantage. It is apparent however that under certain conditions the pressure in chamber 22 will accumulate faster than it can be vented by the running joint 16-17 and in that event the runner would be thrown upward out of alinement with the involute if there were no other devic to take care of this excessive pressure. At this point, however, the automatic feature of my counter-balance comes into action, because the upward movement of the runner causes the piston 24 to open the nipple 23, thereby allowing the pressure water in chamber 22 to escape through the nipple and be discharged as through a drain back into the well or elsewhere. This action'causes the runner to drop back into alinement and the piston 24: to close the nipple 23, thereby reestablishing equilibrium.

Having fully described my invention what I desire to claim and secure by Letters Patent is:

1. In a centrifugal pump, the combination with the runner and its involute of a pressure chamber, an inlet leading from the involute to said chamber, two outlets from said chamber, one of which communicates with the interior of the runner while the other leads away from the runner,- and a valve controlling the latter outlet adapted to be automatically opened by excess of pressure in the pressure chamber and to drain the pressure water therefrom.

2. In a centrifugal pump, the combination of a case, a runner mounted on a shaft the pump, an intermediate fixed plate between the bottom of the pump case and the bottom of the said cylindrical member, a running joint between said intermediate member and said cylindrical member,

-whereby the latter is allowed to revolve with the runner, and means operated by the vertical movement of the runner for controlling the opening in the member closing the bottom of the pump case.

3. In a centrifugal pump, the combina tion of a case, a runner mounted on a shaft and revoluble in the case, a suction inlet passage on one side of the runner, a cylindrical member attached to the runner on the side opposite the suction inlet and partly closed at the bottom, a running joint between the side of the cylindrical member and the pump case, a down turned flange on the inner edge of the bottom of the cylindrical member, a plate closing the bottom of the pump case and provided with an opening leading away from the pump, an intermediate fixed plate between the bottom of the pump case and the bottom of the said cylindrical member, having an upturned flange forming a running joint with the downturned flange on the inner edge of the bottom of the cylindrical member, and means operated by the vertical movement of the runner for controlling the opening in the plate closing the bottom of the pump case.

4;. In a centrifugal pump, the combination of a case, a runner mounted on a shaft and revoluble in the case, a suction inlet passage and a flange projecting from the runner into the suction inlet passage and forming a running joint with the side of the case, a flange of lesser diameter projecting from the opposite side of the runner, a plate closing the side of the case opposite the suction inlet, a smaller plate secured thereto and spaced therefrom, an upturned flange on the smaller plate forming a running joint with the said flange of lesser diameter, an outlet passage for said chamber and means attached to the runner for controlling said passage.

5. In a centrifugal pump, a case, a runner mounted on a shaft and revoluble in the case, a suction inlet on one side of the case, a counter-balancing pressure chamber on the opposite side, a fixed plate excluding a portion of the area of said chamber, a plate on the runner forming a running joint with said fixed plate closing and excluding the area embraced by the fixed plate from the remainder of the chamber, a discharge passage for said chamber lead ing away from the pump, and means attached to the runner for controlling said passage.

6. In a centrifugal pump, a case, a runner mounted on a shaft and revoluble within the case, a suction inlet passage concentric with the shaft on one side of the case,

an annular flange projecting from the runner into said inlet and forming a running joint therein, a corresponding flange projecting from the opposite side of the runner and forming a running joint with the case, a plate having a depending flange attached to said lower runner flange, a plate closing the bottom of the case, a circular plate of smaller diameter secured thereto and provided with a flange which forms a running joint with said depending flange, whereby an annular pressure chamber is formed, and means operative by the axial movement of the runner for controlling the pressure in said chamber.

7. In a centrifugal pump, a runner, a counter-balancing device for the runner comprising a pressure chamber, a running joint between said chamber and the discharge side of the pump, a running joint between said chamber and the suction side of the pump, fluid being adapted to circulate from the discharge side of the pump through said first running joint, said pressure chamber, said second running joint and through said suction inlet so as to maintain a definite pressure in said pressure chamber to counter-balance the runner during normal running conditions of the pump, said pressure chamber provided with an outlet leading from said runner and a valve in said outlet adapted automatically to open said outlet to allow fluid to escape from said chamber when the pressure in said chamber becomes excessive.

8. In a centrifugal pump, a runner, a counter-balancing device for the runner comprising a pressure chamber, a running joint between said chamber and the discharge side of the pump, a running joint between said chamber and the suction side of the pump, fluid being adapted to circulate from the discharge side of the pump through said first running joint, said pres sure chamber, and second running joint and through said suction inlet, so as to maintain a definite pressure in said pressure cha1n ber to counter-balance the runner during normal running conditions of the pump, and means for reducing the pressure in said pressure chamber to normal when the pressure in said chamber becomes excessive.

In testimony whereof, I have hereunto set my hand at San Francisco, California, this 24th day of October, 1914.

JOHN A. YEATMAN.

In presence of- ALAN FRANKLIN, P. S. PIDWELL.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. G. 

